3m limit to building over a sewer

[Alchemist]

Hi 

I would appreciate some help on this. The NDN are having a conservatory built -now. When they applied for planning permission, one of the conditions was that they were not to build within 3 m of a public/shared sewer. There was an older conservatory built on the site in 1998 and this was built over the shared sewer. The sewer is shared between No 1,2, and 3. We are No1 and the sewer egresses through our patio. There is a a history of problems with this sewer. It is No2 that is building the conservatory. No 2 have demolished the old conservatory and applied for planning permission for a new conservatory. This is much bigger and heavier that the old one...hence we think, the `3m` condition. The conservatory constructor is Anglian. We have had a look at what they are doing on site and it would seem that the whole width of the conservatory will be built over the sewer and because they are building up to the boundary the `3m` condition actually applies to 3m of our property. I should add that the sewer is very very close to our foundations.

 

Is this building over a sewer by Anglian very naughty or, if I complain, will they just get a smack on the wrist and get a build over agreement in retrospect? Thanks for your help

 

Kemyst

 

 

[RobLe]

I don’t think that 3m is a hard and fast rule.  Our neighbour has been advised by his architect (and paid for plans) that he can build over his shared sewer for a length of no more than 6m.  The neighbour is ‘upstream’ of us, there’s just 2 properties above him.  He hasn’t got pp yet mind, so this may not be right!  His drawings show a staggered extension, part beyond the sewer, part constrained by it, with foundations running alongside and within 1m of the sewer.

There are a lot of problems with our sewer, the area is quite flat so it doesn’t slope much.  I’m not aware of problems in the 6m stretch in question.  We’re in Cambridge.

[Alchemist]

Thanks for that, Rob. Who knows what how the planning people think. Some people get away with major infringements others have to rip the building down for some silly thing. However the pp blurb does state 3m.]

Thanks again.

[Temp]

Planning conditions have to meet a number of tests or they can be appealed. Ii might be wrong but I'm a bit surprised it's possible to impose a 3m rule as a planning condition. I suppose it depends on the exact wording. 

 

For example its technically possible to build over a sewer without causing issues if cost is no object - for example by digging it up and replacing it with a more robust design. This solution might deal with any possible planning reason for the condition relating to the fragility of the pipe. That might make the condition unenforceable or at least open to a challenge.

 

Obviously some bylaw or water company regulation might also prevent building too close but that's different to a planning condition.

 

[Gus Potter]

17 hours ago, Alchemist said:

Hi 

I would appreciate some help on this. The NDN are having a conservatory built -now. When they applied for planning permission, one of the conditions was that they were not to build within 3 m of a public/shared sewer. There was an older conservatory built on the site in 1998 and this was built over the shared sewer. The sewer is shared between No 1,2, and 3. We are No1 and the sewer egresses through our patio. There is a a history of problems with this sewer. It is No2 that is building the conservatory. No 2 have demolished the old conservatory and applied for planning permission for a new conservatory. This is much bigger and heavier that the old one...hence we think, the `3m` condition. The conservatory constructor is Anglian. We have had a look at what they are doing on site and it would seem that the whole width of the conservatory will be built over the sewer and because they are building up to the boundary the `3m` condition actually applies to 3m of our property. I should add that the sewer is very very close to our foundations.

 

Is this building over a sewer by Anglian very naughty or, if I complain, will they just get a smack on the wrist and get a build over agreement in retrospect? Thanks for your help

 

Kemyst

 

 

This can be quite confusing. I'll come back to @Alchemist in a bit.

 

Al long time ago we had the "Water Board" They covered most of the UK. The regulations were standardised, in Scotland for example we had the Sottish Office who applied the UK regs. We had the early NHBC who were a public body that covered all of the UK. The Water Board was split up and privatised in England, in Scotland an arms length body was formed called Scottish Water. But they all in the main still apply the same standards thoughout the UK to this day.

 

For the uninitiated. For older housing imperial sizes of drains are installed. Generally a private sewer (usually 4", inches inside diameter, often made of clay) is a drain that serves your house only, it belongs to you and you are responsible for it.  A public sewer is one that often serves say 2 or more houses and often runs down the back of houses, if it is a shortish terrace, pipe is usually 6" inside diameter. This public sewer does not belong to you. It is a water company asset and it belongs to them and they have responsibility for maintaining it. This applies in most parts of the UK. A Main sewer is usually found under the road, this is often big and deep, can be 9" up to massive.

 

Now the planners may have put a general condition on the application.. the 3.0m. However this is a general condition. Planning is to do with what the buiding looks like visually and so on. It has little to do with the Engineering aspect and Building Control Compliance. The drains are hidden below the ground. They may have put this condition on as the planning application was poor and lacked information. The planning condition could be lifted if an appropriate design solution that satisfies both the building regulations and the water company regulations was put forward.. which we often do in the case of a public sewer, main sewers are a different animal.

 

@Alchemist If you have concerns then you could consider the following.

 

Make sure you have a set of record photos of your house both before and up to date... call this a delapidations survey. An old trick is to show a copy of the day's paper in the photographs. This means that the photo must have been taken on or after the day of publication. Send this to a friend so you have record. 

 

Next maybe consider writing to Building Control and say they are building on the boundary and that you are concerned about the following matters of public safety:

 

1/ Is the structure compliant with the fire regulations as a fire boundary condition applies.

2/ Are the foundations or superstructure in any way encroaching on your property, even if not, have they been designed not to compromise the bearing capacity of the soil for example below your foundations that your house relies upon to hold it up. Point out that the drains are very close to your house and that you are concerned that an appropriate site investigation has not been conducted.

3/ Has the depth, location and size of the drain been established and has an appropriate Structural Engineering solution been developed that encompases the temporary works and permenant design that will ensure your house remains stable. Maybe point out that the drains are very close to your house and that you are concerned that an appropriate site investigation has not been conducted?

4/ Does the design comply with the building regulations. In particular with respect to differential movement (due to the change in loading) that could result in cracking of the drain and thus leakage from the drain that would compromise the integrity of the soil under your foundations.

5/ If any work starts pop you camera over the fence and take some photos of what you can see!

 

The objective of the above is to try and make sure that what is being built will not compromise your house and to have a record of such communication regarding your concerns. It is difficult to resist a valid planning application, that is life.

 

Have you checked if in England that the party wall act does not apply. Is there a change in ground level, maybe a shared retaining wall?

 

While the above is a bit forensic bear in mind that you want to get on with your neighbours in the long run, most folk do so diplomacy is a key requirement here. It maybe that even though they are building something bigger you can negotiate a wall finish on the side you see that is to your liking in return for not you rocking the boat too much?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[saveasteading]

There are 'hard and fast' rules about mains sewers because of the seriousness of any problem, and access for maintenance.

It sounds as is yours is a private stub only affecting your 3 houses.

Does it belong to the 3 owners or the sewage company?

 

What would be the issue if there was a problem under the conservatory? 

 

If it could affect your drains working then you should speak to the BCO and the neighbour. Otherwise perhaps it isn't your problem but theirs?

 

As to the 3m rule, it is variable. I once built a warehouse/retail unit over a very big sewer, with the approval of the drainage company (and the owner of course).

The owner had to agree in writing that he would allow access through his building (including excavation) if ever required.

It saved a stack of money in diverting the sewer.

We designed the building with a very wide portal space so that it would not be affected if this was to happen, and so that our excavations were well clear.

 

Your situation is lower scale of course. If the conservatory has new footings then they might add load and damage the drain.

But it would need lots more info to understand fully.

 

 

[Temp]

13 minutes ago, saveasteading said:

It sounds as is yours is a private stub only affecting your 3 houses.

 

Perhaps not since 2011?...

 

https://www.ofwat.gov.uk/nonhouseholds/supply-and-standards/responsibility-supply-pipes/

 

 

[Alchemist]

Well thank you for your responses. They are gratefully received. Ok the situation is as follows. The sewer is shared between the three houses. I believe this defines it as a public sewer. The sewer gets clogged about three times a year due to a fault where the sewer joins the main sewer. When this happens, our patio gets flooded with sewage and the water board unclogs it. Without putting too fine a point on it, the blockage is always `sanitary` products (which we don`t use)  It is always us that has to organise this. We have had constant bullying over the construction of the conservatory for eighteen months now. My wife has been reduced to tears many times. The old conservatory was constructed before the Water Board adopted the sewer and was built over the sewer. We don`t know if there was any mention of this sewer in the old planning permission. When planning permission was requested for the construction of the newer, bigger conservatory, a proviso was definitely put into the approval certificate via the Water Board, that they were not to build within 3m of the sewer (I have a copy). This will be 3m along  and into my patio and just 2ft from my extension wall.  The entire conservatory will be constructed over the sewer. A relative seems to think that because old conservatory was built over the conservatory, than the 3m condition will not apply to the new conservatory. 

 

We have come up against type of thing this before. Planning stated that, because the old conservatory `overdeveloped` the site (their words). then if the new conservatory over developed the site even more well, that was ok. I have given up trying to fathom out the logic system the planning department work to. For instance 80% of the conservatory will contravene the 45 degree rule but hey that `OK its only guidance we can apply it when we want to!`

 

I`d really appreciate some guidance on the sewer they have definitely not strengthened it or done any modifications to it just build over it.

 

Thanks for your help

[saveasteading]

As someone else mentioned, this is not the sort of thing the planners look into normally. If the rule is imposed by the sewage company then that is who should control it. I don't recall any time when a sewer company did not take it seriously, so would expect them to be hard on this.

Bullying often works doesn't it. Sorry to hear of that. You either accept it or stand up to it, and I cannot advise what is better for your circumstances.

[Alchemist]

Well thanks for your help guys!

 

Build-over the sewer - agreed

No inspection chamber or drain cover in their property -agreed,

Rain water to flow off roof into sewer - agreed

Rain water in other 1/2 roof to drain onto garden their which is higher than ours - agreed

No CCTV of sewer; no inspection after completion -  agreed.

 

I`m too heartbroken to comment.

[saveasteading]

OK. But if the sewer blocks, it is their building at risk.

When you say 'agreed' is that not by the water company?

[Alchemist]

Yes it seems that all the above has been agreed by Welsh Water.

 

Thanks saveastaeing